Canon has announced that the latest firmware updates for its EOS-1D Mark IV (Version 1.1.0) and EOS 5D Mark II (Version 2.0.9) DSLRs are now available for download. Details of the exact firmware fixes and improvements are shown below.

EOS-1D Mark IV firmware Version 1.1.0
Firmware Version 1.1.0 for the EOS-1D Mark IV incorporates the following improvements and fixes:

Improves the writing/reading speeds when using UDMA 7-compatible CF cards.

Fixes a phenomenon that occurs when using high-capacity (32 GB or greater) CF cards: If either a CF card with only a little available space remaining or the battery is removed and then reinserted into the camera, and then the user attempts to start shooting movies immediately, shooting may stop.

Corrects some mistakes in the menu screens displayed in Arabic and Portuguese.

Before downloading firmware Version 1.1.0 please ensure that you read the entire contents of this link for the Mac version of the firmware and this link for the Windows version of the firmware.

EOS 5D Mark II firmware Version 2.0.9
Firmware Version 2.0.9 for the EOS 5D Mark II incorporates the following improvements and fixes:

Improves the writing/reading speeds when using UDMA 7-compatible CF cards.

Fixes a phenomenon that occurs when Custom Function C.Fn III-2 is set to [5: IS start] to assign IS start to the AF stop button on the lens: When used with lenses that do not have an AF stop button, the IS function will not work.

Corrects some mistakes in the menu screens displayed in Arabic, Portuguese, Spanish, and Thai.

Before downloading firmware Version 2.0.9 please ensure that you read the entire contents of this link for the Mac version of the firmware and this link for the Windows version of the firmware.